1995 Ford Escort Evaporative Canister?

I have the 1.9 engine on the Escort Hatchback.
I was just wondering what the canister (looking at the engine compartment from the front outside of the car) on the passenger side in the back of the engine compartment probably about 12" down was. Someone who was working on my car hit it with a drill bit and it had an impressive depressurization.

Would it be for the AC? What would this pressurized canister be called?

Thanks